The present invention relates to a heat exchanger, and more particularly, to a plate-fin continuous tube heat exchanger.
Plate-fin tube heat exchangers typically include brazed hairpin and return bend. copper tubes, the joints of which can leak refrigerant and require manufacturing time and effort. In addition, existing plate-fin and continuous tube heat exchangers are typically limited to a single circuit within a particular air distribution zone because the circuit tubes do not cross between zones.
A non-uniform airflow distribution through these heat exchangers, often driven by geometric constraints, can result in superheat levels that vary dramatically for each circuit. A circuit with a higher airflow rate passing over its tubes will have higher overall heat transfer to the refrigerant, which results in a higher level of superheat within that circuit as compared to circuits exposed to lower airflow rates. Because superheated refrigerant transfers heat less efficiently than saturated vapor refrigerant or a liquid and vapor refrigerant mixture, single-zone circuiting in existing continuous tube heat exchangers can result in an unbalanced superheat condition within one or more tube circuits and thermal inefficiencies in the heat exchanger.